The present invention relates to a fuse for use in a semiconductor structure, and more particular to a novel semiconductor fuse which can be employed with low dielectric constant materials as well as copper wiring. The novel fuses of the present invention do not substantially damage the surrounding semiconductor structure when the fuse is deleted. Moreover, the novel fuse of the present invention affords a greater opportunity for providing semiconductor structures having denser fuse layouts as well as a higher number of fuses thereon. The present invention also provides methods of forming the novel semiconductor fuses of the present invention.
In today""s generation of semiconductor chips, there are up to 5000 fuses per chip with as many as 1000-4000 deletes per second required to make laser blow technology economically feasible. In future chips, the number of fuses per chip may grow even higher, e.g. 50,000 or more.
In conventional fusing, either laser delete of the metal conductors or electrically blowing the polysilicon fuse links is employed. Both of these existing technologies involve relatively large amounts of energy to superheat and delete the fuse. Such prior art methods are detrimental to the integrity of low dielectric constant materials, particularly foam type materials, thus limiting their use as interlayer dielectric films.
Because of line to line coupling which slows signal propagation, there is a trend for the interlevel dielectric to be composed of a low dielectric constant material such as a polyimide nanofoam or a porous glass such as zero gel. The low dielectric constant materials are not solids and thus they will collapse when their thermal budget or glass transition temperature, Tg, (about 300xc2x0 C.) or mechanical strength is exceeded. Moreover, to improve signal propagation in semiconductor chips, high conductance materials such as copper are now being used as the conductive material.
There are two problems associated with using the above materials. First, conventional laser blowing (or even electric blowing) will damage the low dielectric constant material causing it to collapse, changing its dielectric constant and integrity. When copper or another suitable high conductance material is used, particles of the high conductance material may be released into the pores of the low dielectric constant material. This release may cause a potential reliability problem which could compromise the performance of the basic local structure of the semiconductor chip.
In view of the drawbacks with prior art blowing methods, there is a need for developing a new and improved semiconductor fuse structure which contains a fuse that causes little or no damage to the surrounding structure when the fuse is deleted. The fuse must also offer the opportunity for denser fuse layouts and the capability of providing a higher number of fuses in the semiconductor structure. Any new fuse structure must be able to use low dielectric constant materials as well as high conductance materials, e.g. Cu.
One object of the present invention is to provide a method of fabricating a semiconductor structure having a fuse which is compatible with a wide variety of materials, including low dielectric constant materials and high conductance materials.
A further object of the present invention is to provide a method of manufacturing a fuse for a semiconductor structure which when blown does little or no damage to the surrounding structure.
A still further object of the present invention is to provide a method of fabricating a semiconductor structure having a denser fuse layout as well as a higher number of fuses than conventional semiconductor fuse structures.
These and other objects and advantages can be obtained using one of the methods of the present invention. The first method of the present invention for forming a semiconducting fuse comprises the steps of:
(a) providing a semiconductor structure, said structure comprising a least one wiring level formed on a semiconductor substrate;
(b) forming a first dielectric layer on a surface of said semiconductor structure;
(c) forming a first and second conductive line in said first dielectric layer, each conductive line having an end, said ends being in proximity to each other;
(d) forming a second dielectric layer on said first dielectric layer covering said first and second conductive lines;
(e) forming a hole in said second dielectric layer, said hole at least exposing a portion of said first and second conductive line; and
(f) filling said hole with a conductive fuse material so as to provide an electrical connection between the first and second conductive lines.
It is noted that the hole provided in step (e) is at least to the upper surface of the first and second conductive lines. In one embodiment of the present invention, the hole extends between the ends of the first and second conductive lines. In this embodiment, the fuse material forms an electrical contact at the ends of the conductive lines. In another embodiment of the first method of the present invention, a passivating layer or a polish stop layer is positioned between said first and second dielectric layers.
The second method of the present invention comprises the steps of:
(a) providing a semiconductor structure, said structure comprising at least one wiring level formed on a semiconductor substrate;
(b) forming a first dielectric layer on a surface of said semiconductor structure;
(c) forming at least one electrically connected conductive line in said first dielectric layer;
(d) forming a second dielectric layer on said first dielectric layer covering said at least one electrically connected conductive line;
(e) forming a hole in said second dielectric layer, said hole bisecting said at least one electrically connected conductive line into a first non-electrically connected conductive line and a second non-electrically connected conductive line, each line having an end, wherein said ends are in proximity to each other; and
(f) filling said hole with a conductive fuse material so as to provide an electrical connection between the first and second conductive lines.
Another aspect of the present invention relates to a semiconductor fuse structure. Specifically, the fuse structure of the present invention comprises:
a semiconductor structure having at least one wiring level formed on a semiconductor substrate;
a first dielectric layer formed on a surface of said semiconductor structure;
a first and second conductive line formed in said first dielectric layer, each conductive line having an end, wherein said ends are in proximity to each other;
a second dielectric layer formed on said first dielectric layer covering said first and second conductive lines, said second dielectric layer having a contact hole therein exposing said first and second conductive lines; and
a conductive fuse material formed in said contact hole so as to provide an electrical connection between said first and second conductive lines.